Armadillosuchus: One bad crocodyliform

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Life restoration of the head of Armadillosuchus. From Marinho and Carvalho (2009).


ResearchBlogging.org When I was trying to come up with a title for this post I almost went with "Armadillosuchus: An armored crocodyliform you wouldn't want to mess with." Obviously I changed my mind. Not only was the title too long, but it was redundant to boot. All crocodyliformes (which includes living crocodylians) are "armored" in that they have little bony plates called osteoderms (primarily on the dorsal, or top, side of their bodies) beneath their scales, which in turn overlay a layer of bony plates called osteoscutes. Crocodyliformes are tough!

The newly-described crocodyliform Armadillosuchus from the Late Cretaceous deposits of Brazil, however, was carrying a more bizarre complement of armor. Right behind its head was an armored dome of hexagonal plates. This bony buckler was rigid, but could be moved independently of the head so that the neck was not always locked in one position. Now comes the really interesting part. Behind this "cervical shield" was a series of about seven mobile armored bands. (What the researchers call "mobile-banded body armor.") This is very similar to what is seen in living armadillos, hence the croc's name Armadillosuchus. This crocodyliform had "armadillo-like" armor even before the mammals did!

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Armadillosuchus. The head is to the left, followed by the cervical shield and mobile-banded body armor. From Marinho and Carvalho (2009).


Yet Armadillosuchus was even stranger still. Despite the claim that crocodiles have persisted "unchanged for millions of years" there was a greater past diversity of crocodyliform types than is represented today. Armadillosuchus is a fine example of this. In addition to the armor bands it had large hand claws, a shortened snout, and teeth that differed throughout its mouth (contrary to the "homodont" condition I was taught to associate with reptiles in elementary school).

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The partial upper and lower jaws of Armadillosuchus. The front is to the right. From Marinho and Carvalho (2009).


Indeed, Armadillosuchus had what looked like large, curved "canine" teeth, shorter teeth that stuck out straight forward at the front of the lower jaw, and stubby conical teeth with shearing ridges. The paleontologists who described it were not sure what it ate, but based upon this dental toolkit it may very well have been an omnivore. The large hand claws also suggest that it was a digger, possibly rooting about in the ground after food (again like modern armadillos).

But why all that armor? Was Armadillosuchus at risk of becoming prey to a bigger, badder crocodyliform? Possibly. The area in which it was found, the Bauru Basin, was chock-full of strange crocodyliformes during the Late Cretaceous (including the terrestrial species Montealtosuchus arrudacamposi I wrote about last year). Then again there might be another reason why this crocodyliform had mobile-banded body armor, so we should be careful when asking why it evolved this particular feature. Even so, it is still fascinating that during the Late Cretaceous this part of what is now Brazil was the land of the crocodyliformes; numerous forms have been found there that are unlike anything seen today.

I apologize if this entry seems a little breathless, but it is difficult not to get excited about such a wonderful new species! Who would have guessed that, sometime between 99 and 65 million years ago, there was a short-snouted crocodyliform with "tusks" in its mouth and armadillo-like armor on its back? I never would have imagined it, but the fact that such a form evolved has set my mind reeling. This is why I love paleontology!

Marinho, T., & Carvalho, I. (2009). An armadillo-like sphagesaurid crocodyliform from the Late Cretaceous of Brazil Journal of South American Earth Sciences, 27 (1), 36-41 DOI: 10.1016/j.jsames.2008.11.005

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This is why folks who only look at dinosaurs need to broaden their horizons, there are sooooo many other interesting critters.

Any chance that present-day crocs can sue armadillos for patent infringement?

Funny, when I saw the title, I assumed it was going to be about a certain mount of Armadillosuchus, photos of which have been making the rounds lately, and how bad it is.

A bizarre, amazing creature. I've also noticed the great diversity this family once had: there's a Cretaceous croc from Madagascar that was apparently herbivorous! And by the way, I know I'm dating myself, but exactly when did everyone start spelling "crocodylian" with a "y"? I first noticed that spelling on the cover of a book about Deinosuchus.

By Raymond Minton (not verified) on 10 Jul 2009 #permalink

Mike; Yeah, I meant "bad" as in "'That Shaft is one bad...' "Shut your mouth!'"... I didn't see the awful restoration until after I posted this.

Raymond; My answer to your question is "When Jerry Harris told me to stop using 'crocodilian'", which (IIRC) was in the fall of 2008. I'm sure someone else here better versed in taxonomy/systematics could give you a better answer.

Who would have guessed that, sometime between 99 and 65 million years ago, there was a short-snouted crocodylian with "tusks" in its mouth and armadillo-like armor on its back?

I would have. And here too.:-)

I can see that this is going to be the inspiration for some croc blogging, though...

Rob, I took an intellectual property rights class in law school and believe I'm safe in saying Armadillosuchus has no patent claim, but could probably sue for copyright (patent requires too many formalities and filings).

On a more serious note, your other point is well taken. A lot of the most interesting finds are from other families of creatures, such as mammals and other reptiles. Likewise, there was an interesting paper about the evolution of turtle shells in Science today (http://news.nationalgeographic.com/news/2009/07/090709-turtles-shells-r…). It might do the field good (and get more funding) if people view paleontology as more than dinosaurs...

Raymond, you speak, perhaps, of Chimaerasuchus paradoxus, an Early Cretaceous herbivorous form from China. Frustratingly, I can't find any primary literature on it, but it has stratlingly mammalian dentition.

I think that it's quite obvious that the real reason we have this beast is due to an unholy Mesozoic union between a time traveling Armadillo and a more than healthily receptive crocodile.

By Tor Bertin (not verified) on 10 Jul 2009 #permalink

In all seriousness, that thing is too cool. Yet another mark on my list of remarkably bad ass Gondwanan fauna.

By Tor Bertin (not verified) on 10 Jul 2009 #permalink

Zach Miller wrote:
"Raymond, you speak, perhaps, of Chimaerasuchus paradoxus, an Early Cretaceous herbivorous form from China. Frustratingly, I can't find any primary literature on it, but it has stratlingly mammalian dentition."

No, he means Simosuchus.

For Chimaerasuchus paradoxus, look at:
Wu, X. C. and Sues, H.D. 1996. Anatomy and Phylogenetic Relationships of Chimaerasuchus paradoxus, an Unusual Crocodyliform Reptile from the Lower Cretaceous of Hubei, China. Journal of Vertebrate Paleontology, Vol. 16, No. 4, pp. 688-702
http://www.jstor.org/stable/4523767

For Simosuchus clarki, look at:
Buckley et al. 2000. A pug-nosed crocodyliform from the Late Cretaceous of Madagascar. Nature 405, pp. 941-944. http://dx.doi.org/10.1038/35016061
Dr. Gregory A. Buckley, C. A. Brochu, D. W. Krause, D. Pol, 2004, "Simosuchus clarki" (On-line), Digital Morphology. http://digimorph.org/specimens/Simosuchus_clarki/

At any rate, many crocodylomorphs (even extant crocodylians) display varying amounts of heterodonty. Maybe it's just the extreme cases, like in notosuchians, the "sphenosuchian" Phyllodontosuchus, and a few others that draw attention.

Raymond Wrote:

there's a Cretaceous croc from Madagascar that was apparently herbivorous!

You are talking about Simosuchus clarki from the Upper Cretaceous (Maastrichtian) Maevarano Formation (Buckley et al., 2000).

BTW, thanks for sharing this Brian!! Crocs were indeed very diverse in the past, they are a very interesting group and one of my favorites!!

Buckley, G. A., C. A. Brochu, D. W. Krause & D. Pol. 2000. A pug-nosed crocodyliform from the Late Cretaceous of Madagascar. Nature 405:941-944.

Dom Nardi, #7

Not copyright or patent. Not even trademark. What's being violated here is trade dress, the particular look. I learned about this back when Wizards of the Coast was having trouble when certain D20 publishers were deliberately imitating the look of the D&D 3e books in order to boost sales. Other examples of trade dress include Coca Cola and Pepsi Cola, both of whom aggressively protect the distinctive appearance of their products.

On the other hand, banded armor is not really something you can protect through any legal measure. It's sort of like a mathematical formula or game mechanic, mechanics constrain appearance. Whether you're dealing with a crocodylian, a mammal, or a human wearing banded mail you're going to get the same look. Thus the dillo croc has no grounds for action.

Then again, I'm not a lawyer, and am therefor constrained by common sense.

There are all these wonderful crocs in the fossil record and I'll read scraps about them here and there...

... and nobody ever -- EVER! -- makes enough information available to the layman to make it possible for a poor paleo-geek to draw a reconstruction.

And a species with this kind of really interesting anatomy... It's like teasing a dog, man.

The usage of Crocodylia instead of Crocodilia was recomended by Dundee (1989), as the former is the correct adaptation derived from Crocodylus.

Dundee, H. A. 1989. Higher category name usage for amphibians and reptiles. Systematic Zoology 38(4):398-406.

I am very interested of exactly what characters that are diagnostic that rationalizing calling this a crocodile. I can not see more than the abstract, perhaps you could fill me in?

The whole Crocodilia vs Crocodylia thing is complex and different workers have different views. The 'consensus view', however, is that it's best to restrict Crocodylia to the crown-group: that is, to the clade that includes living crocs, gators and gharials, and all descendants of their most recent common ancestor. The larger group that includes all of the fossil creatures closely related to extant crocodylians has traditionally been called Crocodilia (though Crocodylia has also been used!) so, to avoid confusion, the term Crocodyliformes is used for this far larger clade instead.

If we follow this system, animals like Armadillosuchus are crocodyliforms (formal: Crocodyliformes; vernacular: crocodyliforms), but not crocodylians. Crocodyliforms are part of a more inclusive clade, Crocodylomorpha, that also includes the sphenosuchians. I'd say that Crocodylomorpha conforms most closely to the 'Crocodilia' of tradition, hence 'crocodilians', in the broadest sense possible, are now termed crocodylomorphs. Confused?

Jim Clark proposed this 'new' system in a paper co-authored with Mike Benton in 1988, but Mike has since disowned this and has recently been arguing that Crocodilia should be used in place of Crocodyliformes. Argh!

This is rarely/never explained in the semi-popular or popular literature. It is, however, thrashed out in...

Naish, D. 2001. Fossils explained 34: Crocodilians. Geology Today 17 (2), 71-77.

... which I can send to anyone interested. See also...

Benton, M. J. & Clark, J. M. 1988. Archosaur phylogeny and the relationships of the Crocodylia. In Benton, M. J. (eds) The Phylogeny and Classification of the Tetrapods, Volume 1: Amphibians, Reptiles, Birds. Clarendon Press (Oxford), pp. 295-338.

Jim Clark proposed this 'new' system in a paper co-authored with Mike Benton in 1988, but Mike has since disowned this and has recently been arguing that Crocodilia should be used in place of Crocodyliformes.

Having just recently read the paper in question, I can point out that Mike Benton even disowned the system in the original paper (on p. 297). There was apparently a compromise - Clark got to have his restricted Crocodylia, and Benton got to include Proterosuchidae and Erythrosuchidae in Archosauria.

Oh yeah - some of the bits in this paper (e.g., naming of Crocodyliformes) are sometimes cited as 'Clark in Benton & Clark'.

@Darren: I'd like a copy. (andreasj at gmail dot com)

By Andreas Johansson (not verified) on 15 Jul 2009 #permalink

Crocodylus has its y because Laurentius or whoever coined the genus name didn't know Greek. (It wasn't Linnaeus, who lumped all crocodiles into the species Lacerta crocodilus.)

I've never seen what Darren implies (the two spellings being used as different names).

By David MarjanoviÄ (not verified) on 18 Jul 2009 #permalink

For anyone who is interested, I first read about the herbivorous crocodile in an August 2000 issue of "National Geographic" in the story "Monsters of Madagascar" and the genus hadn't yet been named. I'm glad people have been helpful in identifying this animal, I'll look Simosuchus up because it fits the timeline. A veggie-eating croc sounds as unlikely as a carnivorous cow, but there was apparently more than one, so I'll have to start being more open-minded!

By Raymond Minton (not verified) on 19 Jul 2009 #permalink

A very interesting fossil. But, after reading the paper I am quite disappointed by the lack of a more thorough description of the specimen; barely anything is mentioned about the postcranium and they could have done a better job illustrating the mobile banded shield. Sorry if this sounds like a rant, but I really wanted to know more about this critter.

I agree "For anyone who is interested, I first read about the herbivorous crocodile in an August 2000 issue of "National Geographic" in the story "Monsters of Madagascar" and the genus hadn't yet been named. I'm glad people have been helpful in identifying this animal, I'll look Simosuchus up because it fits the timeline. A veggie-eating croc sounds as unlikely as a carnivorous cow, but there was apparently more than one, so "